[AAVSO-HEN] GRB 090812 VLT redshift

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TITLE:   GCN CIRCULAR
NUMBER:  9771
SUBJECT: GRB 090812 VLT redshift
DATE:    09/08/12 09:02:26 GMT
FROM:    Antonio Deugarte at IAA-CSIC  <deugarte at iaa.es>

A. de Ugarte Postigo (INAF-OAB), J. Gorosabel (IAA-CSIC),
J.P.U. Fynbo (DARK/NBI), K. Wiersema and N. Tanvir (Leicester)
report on behalf of a larger collaboration

We have observed the afterglow of GRB 090812 (Stamatikos et al.
GCNC 9768) using FORS2 at the VLT (Paranal observatory) starting
at 06:54 UT (52min after the burst). In the spectrum we detect strong
absorption lines, including Ly-alpha, SiII, SiII*, CII, SiIV, CIV,  
SiII, AlII,
AlIII, FeII, ZnII, MnII and TiII at a common redshift of 2.452 which we
identify as the redshift of the GRB. We also detect absorption lines  
from an
unidentified intervening system. Further analysis is ongoing.

We acknowledge the excellent support from Paranal staff, in particular
Jonathan Smoker, Cedric Ledoux and Karla Aubel.